JP4741437B2 - Organic EL composite element, organic EL display device and illumination device using the same - Google Patents

Description

  The present invention relates to an organic EL composite element, an organic EL display device using the same, and an illumination device.

  2. Description of the Related Art Conventionally, an organic EL element using electroluminescence (EL) of an organic compound that emits light by injection and recombination of electrons and holes is known. Such an organic EL element emits light having no directivity. Therefore, various studies have been made on such organic EL elements in order to improve the directivity of light emission and color purity.

For example, an organic EL composite element in which a dielectric multilayer film is laminated on the light extraction surface of the organic EL element is disclosed (Shizuo Tokito et al., “Microcavity organic light-emitting strong forward bended red, "emissions", JOURNAL OF APPLIED PHYSICS, September 1999, VOL86, No. 5, pages 2407-2411 (Non-patent Document 1) and JP-A-2005-310539 (Patent Document 1)). However, the organic EL composite element described in Patent Document 1 and Non-Patent Document 1 uses a dielectric multilayer film that is difficult to manufacture. Therefore, there has been a demand for the emergence of a technique that is easier to manufacture than the case of using a dielectric multilayer film and that can improve the directivity of light emission and color purity of the organic EL to the same extent.
JP 2005-310539 A Shizuo Tokyo et al. , “Microcavity organic light-emitting diodes for strong directed pure red, green, and blue emissions”, published in JOURNAL OF APPLIED PHYSICS, September 1999, 1994, LOL. 5, 2407-2411

  The present invention has been made in view of the above-described problems of the prior art, and can be efficiently manufactured without using a dielectric multilayer film that is difficult to manufacture, and to the same extent as when a dielectric multilayer film is used. An object of the present invention is to provide an organic EL composite element capable of realizing high emission directivity and color purity, and an organic EL display device and an illumination device using the same.

  As a result of intensive studies to achieve the above object, the present inventors laminated a liquid crystal film having a photonic band gap that selectively reflects light of a specific wavelength on the light extraction surface of the organic EL element. The organic EL composite element thus produced can be manufactured efficiently without using a dielectric multilayer film that is difficult to manufacture, and has the same high light emission directivity and color purity as when a dielectric multilayer film is used. It has been found that it can be realized, and the present invention has been completed.

That is, the organic EL composite element of the present invention includes at least a light emitting layer , a substrate of any one of glass, quartz, and a light transmissive resin film, a light extraction surface side electrode layer laminated on the substrate, An organic EL element comprising a counter electrode and a silver thin film laminated on the surface of the electrode layer on the light extraction surface side facing the counter electrode ;
A liquid crystal film having a photonic band gap that is selectively reflected on a light extraction surface of the organic EL element and selectively reflects light of a specific wavelength;
Equipped with a,
The liquid crystal film is a liquid crystal film in which a right-handed cholesteric liquid crystal film and a left-handed cholesteric liquid crystal film are laminated, and
A cavity structure is formed by the opposite electrode of the organic EL element and the liquid crystal film;
It is characterized by.

  In the organic EL composite element of the present invention, it is preferable that a selective reflection wavelength region of the liquid crystal film overlaps at least a part of an emission wavelength region of the organic EL element.

  Furthermore, in the organic EL composite element of the present invention, it is preferable that the liquid crystal film has a spiral structure formed of liquid crystal molecules, and the pitch number of the spiral structure is 1-30.

  In addition, the liquid crystal film according to the present invention is preferably obtained by fixing a liquid crystal material after cholesteric alignment in a liquid crystal state.

  Furthermore, in the present invention, the thickness of the silver thin film is preferably less than 50 nm.

  Moreover, the organic EL display device of the present invention comprises the organic EL composite element of the present invention.

  Furthermore, the illuminating device of the present invention comprises the organic EL composite element of the present invention.

  According to the present invention, it is possible to efficiently manufacture without using a dielectric multilayer film that is difficult to manufacture, and to achieve a high degree of light emission directivity and color purity as much as when a dielectric multilayer film is used. It is possible to provide an organic EL composite element that can be used, an organic EL display device using the same, and an illumination device.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

First, the organic EL composite element of the present invention will be described. The organic EL composite device of the present invention includes an organic EL device comprising at least a light emitting layer and an electrode layer,
A liquid crystal film having a photonic band gap that is selectively reflected on a light extraction surface of the organic EL element and selectively reflects light of a specific wavelength;
It is characterized by providing.

  The liquid crystal film according to the present invention is a liquid crystal film having a photonic band gap that selectively reflects light of a specific wavelength, and is laminated on the light extraction surface of an organic EL element. In the organic EL composite element of the present invention, such a liquid crystal film is laminated on the light extraction surface of the organic EL element, thereby forming a cavity structure and selectively reflecting light of a specific wavelength. Enables light confinement within the tee structure. Therefore, in the present invention, such a liquid crystal film sufficiently improves the light directivity and color purity. In addition, since it is not necessary to use a dielectric multilayer film that is complicated and difficult to manufacture, an organic EL composite element can be efficiently manufactured.

In such a liquid crystal film, it is preferable that the selective reflection wavelength region overlaps at least a part of the emission wavelength region of the organic EL element. Thus, by overlapping the selective reflection wavelength region of the liquid crystal film with at least a part of the emission wavelength region of the organic EL element, it becomes possible to selectively reflect light in the overlapping wavelength region with the liquid crystal film. In the cavity structure, light having a wavelength overlapping with the selective reflection wavelength region of the liquid crystal film can be confined. Note that such selective reflection wavelength region (Δλ) depends on the pitch (P) and birefringence (Δn) of the helical structure of the liquid crystal film, and the following formula:
Δλ = P × Δn
(Wherein, [Delta] n is the refractive index for the extraordinary light _{(n e)} the refractive index for ordinary light from _{(n o)} of the value obtained by subtracting (Δn ₌ n e -n _o) shows a.)
It is represented by

  Moreover, as such a liquid crystal film, what a spiral structure is formed with the liquid crystal molecule in a liquid crystal film and the pitch number of the said spiral structure is 1-30 (more preferably 2-15) is preferable. By forming a spiral structure in the liquid crystal molecules in this way, it becomes possible to selectively reflect circularly polarized light in a wavelength region corresponding to the number of pitches of the spiral structure. That is, by providing such a spiral structure, the liquid crystal film functions as a selective reflection filter. If the pitch of such a spiral structure is less than 1, it tends to be difficult to selectively reflect light of a specific wavelength by the liquid crystal film. On the other hand, if it exceeds 30, the effect of selectively reflecting light of a specific wavelength. Appears more strongly, but tends to be difficult to manufacture. When the liquid crystal film is made of smectic liquid crystal, the spiral structure is a layer in which the major axis of the liquid crystal molecules is inclined at a certain angle from the direction perpendicular to each smectic layer, and there is an inclination angle. A structure that is twisted little by little from one layer to the next. Moreover, the number of pitches here means the total number of spiral pitches included in the film thickness direction of the liquid crystal film.

  Moreover, in such a liquid crystal film, the film thickness per pitch is preferably 0.1 to 0.6 μm, and more preferably 0.2 to 0.5 μm. When the film thickness per pitch is less than the lower limit, the visible light region does not overlap with the selective reflection wavelength, and the ratio of the chiral material required is high, so that the glass transition temperature is low and the cholesteric orientation is at room temperature. On the other hand, when the upper limit is exceeded, the visible light region and the selective reflection wavelength also tend not to overlap.

  Further, as such a liquid crystal film, a cholesteric liquid crystal film in which a liquid crystal material is fixed by cholesteric alignment or a chiral smectic liquid crystal film in which a liquid crystal material is fixed by chiral smectic alignment can be suitably used. From the standpoint of widening the margin, it is preferable to use a cholesteric liquid crystal film. Moreover, as such a liquid crystal film, what fixed after making the liquid crystal material cholesteric-aligned is preferable. The chiral smectic liquid crystal film described above includes a chiral smectic C phase from the viewpoint of ease of synthesis of liquid crystal materials, ease of orientation of the helical structure, stability of the helical structure, ease of variable helical pitch, and the like. Alternatively, a chiral smectic liquid crystal film having a chiral smectic CA phase is preferable.

  Further, as such a liquid crystal film, a cholesteric liquid crystal film obtained by laminating a right-twisted cholesteric liquid crystal film and a left-twisted cholesteric liquid crystal film is preferable. By using a liquid crystal film in which right-twisted and left-twisted cholesteric liquid crystal films are laminated in this way, the reflection efficiency of incident light is enhanced, and a cavity structure is effectively formed, resulting in a higher cavity effect. Therefore, the directivity of light emission and the color purity tend to be further improved.

  As a method for producing such a liquid crystal film, for example, a method of fixing the alignment of liquid crystal molecules after applying a solution containing the liquid crystal material on an alignment substrate to form a coating film can be employed. . The method for fixing such a liquid crystal material is not particularly limited, and a method such as photocrosslinking, thermal crosslinking, or cooling can be appropriately employed depending on various physical properties of the liquid crystal material to be used.

  The liquid crystal material is not particularly limited, but from the viewpoint of obtaining a cholesteric liquid crystal film or a chiral smectic liquid crystal film suitable for the present invention, a liquid crystal material capable of fixing the cholesteric alignment or the chiral smectic alignment is preferable. Used. As such a liquid crystal material, either a high molecular liquid crystal material or a low molecular liquid crystal material can be used. Such a liquid crystal material may be any material as long as the final material can exhibit the desired orientation, and a high molecular liquid crystal substance and / or a low molecular liquid crystal substance may be used alone. Alternatively, a mixture of a plurality of high molecular liquid crystal substances and / or low molecular liquid crystal substances may be used.

  As such a polymer liquid crystal substance, various main chain type polymer liquid crystal substances, side chain type polymer liquid crystal substances, or a mixture thereof can be used. Such main chain type polymer liquid crystal substances include polyester, polyamide, polycarbonate, polyimide, polyurethane, polybenzimidazole, polybenzoxazole, polybenzthiazole, polyazomethine, and polyesteramide. Polymer liquid crystal substances such as polyester carbonate type and polyester imide type, or a mixture thereof.

  The side chain type polymer liquid crystal substance has a skeleton chain having a linear or cyclic structure such as polyacrylate, polymethacrylate, polyvinyl, polysiloxane, polyether, polymalonate, polyester, etc. Examples thereof include a polymer liquid crystal substance in which a mesogen group is bonded as a side chain to the substance, or a mixture thereof.

  Further, preferred examples of the polymer structural unit include an aromatic or aliphatic diol unit, an aromatic or aliphatic dicarboxylic acid unit, and an aromatic or aliphatic hydroxycarboxylic acid unit.

  Further, the low-molecular liquid crystal substance includes saturated benzene carboxylic acid derivatives, unsaturated benzene carboxylic acid derivatives, biphenyl carboxylic acid derivatives, aromatic oxycarboxylic acid derivatives, Schiff base derivatives, bisazomethine compound derivatives, Compounds exhibiting liquid crystallinity with a reactive functional group introduced at the terminal, such as azo compound derivatives, azoxy compound derivatives, cyclohexane ester compound derivatives, sterol compound derivatives, etc., and compounds exhibiting liquid crystallinity among the above compound derivatives And a composition in which a crosslinkable compound is added.

  Moreover, when manufacturing a cholesteric liquid crystal film, among such liquid crystal materials, the main chain type polymer liquid crystal substance should be used from the viewpoint that the material itself can be easily synthesized and the film can be easily manufactured. It is particularly preferable to use a polyester-based main chain type polymer liquid crystal substance. Moreover, as a liquid crystal material of such a cholesteric liquid crystal film, for example, a liquid crystalline polyester composition described in JP-A-11-124492 can be suitably used.

  Moreover, when producing a chiral smectic liquid crystal film, a chiral agent or an optically active unit may be appropriately introduced into the liquid crystal material. Such a chiral agent is not particularly limited, and a known chiral agent can be appropriately used. Moreover, the optically active unit is not particularly limited, but 2-methyl-1,4-butanediol, 2,4-pentanediol, 1,2-propanediol, 2-chloro-1,4-butane. Examples thereof include diols, 3-methyladipic acid, naproxen derivatives, camphoric acid, binaphthol, menthol or cholesteryl group-containing structural units, or units derived from these derivatives (for example, derivatives such as diacetoxy compounds). Moreover, the compounding amount of such a chiral agent, the introduction amount of the optically active unit, and the like are not particularly limited, and can be appropriately changed according to the design of the target liquid crystal film.

  Furthermore, when the alignment structure formed in the liquid crystal state is fixed by thermal crosslinking or photocrosslinking, it is preferable to include a liquid crystal material having a functional group or a site that can undergo a crosslinking reaction by heat or light. Examples of such functional groups include acryl groups, methacryl groups, vinyl groups, vinyl ether groups, allyl groups, allyloxy groups, glycidyl groups and other epoxy groups, isocyanate groups, isothiocyanate groups, azo groups, diazo groups, azide groups, Examples thereof include a hydroxyl group, a carboxyl group, and a lower ester group, and an acryl group and a methacryl group are particularly preferable. Examples of the site capable of crosslinking reaction include sites containing molecular structures such as maleimide, maleic anhydride, cinnamic acid and cinnamic acid esters, alkenes, dienes, allenes, alkynes, azos, azoxys, disulfides, polysulfides, etc. Is mentioned. These cross-linking groups and cross-linking reaction sites may be contained in the liquid crystal material itself constituting the liquid crystal material, but a non-liquid crystalline material having a cross-linking group or site may be added to the liquid crystal material separately.

  The alignment substrate is not particularly limited as long as it can support a cholesteric liquid crystal film. For example, polyimide, polyamide, polyamideimide, polyphenylene sulfide, polyphenylene oxide, polyetherketone, polyetheretherketone Polyether sulfone, polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyarylate, triacetyl cellulose, epoxy resin, phenol resin film, or uniaxially stretched film of these films can be used. Some of these films exhibit sufficient alignment ability for liquid crystal materials used in cholesteric liquid crystal films without performing processing for expressing alignment ability again, but the alignment ability is insufficient. In the case where it does not show orientation ability, or the like, a process of stretching under moderate heating, a so-called rubbing process in which the film surface is rubbed in one direction with a rayon cloth, etc., polyimide, polyvinyl alcohol, silane coupling agent, etc. on the film A film that is appropriately subjected to a rubbing process for providing an alignment film made of the above-mentioned known aligning agent, an oblique deposition process such as silicon oxide, a process appropriately combining these, or the like may be used. Furthermore, as such an alignment substrate, various glass plates provided with regular fine grooves on the surface may be used. Moreover, it does not restrict | limit especially as an alignment film of such an alignment substrate, Although a well-known alignment film can be used suitably, the polyimide film which gave the rubbing process can be used suitably.

  In addition, the solvent used for the preparation of the solution containing the liquid crystal material to be coated on such an alignment substrate is not particularly limited. For example, hydrocarbons such as toluene, xylene, butylbenzene, tetrahydronaphthalene, decahydronaphthalene, etc. , Ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol dimethyl ether, ethers such as tetrahydrofuran, ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ethyl acetate, butyl acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, ethyl lactate , Esters such as γ-butyrolactone, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, etc. Amide, dichloromethane, carbon tetrachloride, tetrachloroethane, halogenated hydrocarbon such as chlorobenzene, butyl alcohol, triethylene glycol, diacetone alcohol, alcohol such as hexylene glycol. These solvents can be appropriately selected and used according to the type of the liquid crystal material to be used, and may be appropriately mixed and used as necessary. Further, the concentration of such a solution varies depending on the molecular weight and solubility of the liquid crystal material used, the thickness of the target liquid crystal film, etc., but cannot be determined unconditionally, but is preferably about 1 to 60% by mass, It is more preferable that it is 3-40 mass%.

  In addition, a surfactant may be added to the solution containing the liquid crystal material in order to facilitate application. Examples of such surfactants include cationic surfactants such as imidazoline, quaternary ammonium salts, alkylamine oxides, polyamine derivatives, polyoxyethylene-polyoxypropylene condensates, primary or secondary surfactants, and the like. Secondary alcohol ethoxylate, alkylphenol ethoxylate, polyethylene glycol and its esters, sodium lauryl sulfate, ammonium lauryl sulfate, amines of lauryl sulfate, alkyl-substituted aromatic sulfonate, alkyl phosphate, aliphatic or aromatic sulfonic acid formalin condensate Anionic surfactants such as, amphoteric surfactants such as laurylamidopropylbetaine and laurylaminoacetic acid betaine, non-ionic surfactants such as polyethylene glycol fatty acid esters and polyoxyethylene alkylamine Surfactant, perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkyl ethylene oxide adduct, perfluoroalkyltrimethylammonium salt, perfluoroalkyl group / hydrophilic group-containing oligomer, perfluoroalkyl / lipophilic Fluorine-based surfactants such as group-containing oligomer perfluoroalkyl group-containing urethanes. The amount of such a surfactant added depends on the type of surfactant, the type of solvent, or the alignment film of the alignment substrate to be applied, etc., but usually 10 ppm to 10% as a ratio to the mass of the liquid crystal material, Preferably it is 50 ppm to 5%, more preferably 0.01% to 1%.

  Moreover, in order to improve the heat resistance and the like of the liquid crystal film to be obtained, a crosslinking agent such as a bisazide compound or glycidyl methacrylate is added to the solution containing the liquid crystal material, so that the expression of the cholesteric liquid crystal phase is not hindered. It can also be crosslinked in a later step. In addition, a polymerizable functional group having a basic skeleton such as a biphenyl derivative, a phenylbenzoate derivative, or a stilbene derivative into which a functional group such as an acryloyl group, a vinyl group, or an epoxy group is introduced is introduced into a liquid crystal material in advance to express a cholesteric phase and to crosslink. You may let them.

  The application method is not particularly limited as long as the uniformity of the coating film is ensured, and a known method can be appropriately employed. Examples of such a coating method include a roll coating method, a die coating method, a dip coating method, a curtain coating method, and a spin coating method. Moreover, you may put the solvent removal (drying) process by methods, such as a heater and hot air spraying, after application | coating.

  In addition, after fixing the liquid crystal molecules on the alignment substrate, a method of mechanically peeling using a roll or the like at the interface between the alignment substrate and the liquid crystal film, mechanically after being immersed in a poor solvent for all structural materials A method of peeling, a method of peeling by applying ultrasonic waves in a poor solvent, a method of peeling by changing the temperature using the difference in thermal expansion coefficient between the alignment substrate and the liquid crystal film, the alignment substrate itself, or on the alignment substrate A single liquid crystal film can be obtained by dissolving and removing the alignment film. Since the peelability varies depending on the composition ratio of the liquid crystal material to be used, the adhesion to the alignment substrate, and the like, it is preferable to appropriately employ a method most suitable for the system. The obtained liquid crystal film may not be self-supporting depending on the film thickness, but in that case, a substrate preferable in terms of optical properties, for example, polymethacrylate, polycarbonate, polyvinyl alcohol, polyether sulfone, polysulfone, polysulfone, It is desirable to fix and use an adhesive or a pressure-sensitive adhesive on a plastic substrate such as arylate, polyimide, amorphous polyolefin, or triacetyl cellulose because of the strength and reliability of the liquid crystal film.

  The organic EL device according to the present invention includes at least a light emitting layer and an electrode layer. The light emitting layer in such an organic EL element is a layer that emits light by recombination of electrons and holes injected from an electrode layer or the like. The light emitting layer material for forming such a light emitting layer is not particularly limited, and a known material capable of forming the light emitting layer of the organic EL element can be appropriately used. In addition, the method for forming such a light emitting layer is not particularly limited, and a known method can be appropriately employed. For example, known methods such as a vacuum deposition method, a spin coating method, a casting method, an LB method, and an ink jet method are used. It is possible to adopt a method of forming a film by the thinning method. Furthermore, the thickness of the light emitting layer is not particularly limited, and can be appropriately changed according to the design of the target organic EL element. Moreover, in such a light emitting layer, you may contain a well-known dopant suitably from a viewpoint of luminous efficiency improvement or lifetime improvement.

  The electrode layer in the organic EL element is a layered electrode that enables injection of electrons and holes into the light emitting layer. In the organic EL device according to the present invention, the electrode on the light extraction surface side of the anode and the cathode may be layered, and the other shape is not particularly limited.

Such an anode is preferably formed of an electrode material such as a metal, an alloy, an electrically conductive compound and a mixture thereof having a high work function (4 eV or more). Examples of such electrode materials include metals such as Au, conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ and ZnO, and amorphous and transparent materials such as IDIXO (In ₂ O ₃ —ZnO). Examples thereof include materials that can produce a conductive film. The method for producing such an anode is not particularly limited, and a known method can be appropriately employed. For example, a pattern having a desired shape is formed by photolithography after an electrode material is formed into a thin film by a method such as vapor deposition or sputtering. You may employ | adopt the method of forming.

Moreover, as a cathode, what is formed with electrode materials, such as a metal with a small work function (4 eV or less), an alloy, an electroconductive compound, and these mixtures, is preferable. Examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among such electrode materials, a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function value than this, such as magnesium / Silver mixtures, magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. Further, the method for producing such a cathode is not particularly limited, and a known method can be appropriately employed. For example, a method for producing a cathode by forming a thin film of an electrode material by a method such as vapor deposition or sputtering, etc. Can be adopted.

  In the organic EL device according to the present invention, both the anode and the cathode may be formed of a transparent or translucent material so that light can be emitted from both the anode and the cathode. From the viewpoint, it is preferable that only one of the anode and the cathode is formed of a transparent or translucent material, and the light extraction surface is formed on one electrode side.

  In addition, such an organic EL element preferably further includes a silver thin film formed on the electrode layer. By further providing such a silver thin film, the directionality of light emission and color purity of the obtained organic EL composite element tend to be further improved. The reason why the above-described effects are obtained by the silver (Ag) thin film is not necessarily clear, but the present inventors infer as follows. That is, first, the Ag thin film has a function of forming a cavity structure in the organic EL element, and serves as a reflector that confines light emitted from the light emitting layer. The Ag thin film can also serve as an electrode. The Ag thin film has an optimal work function that is important for laminating the organic EL element, and the effect of the formed cavity structure is great. For this reason, the present inventors speculate that by using a silver thin film in combination with the above-described liquid crystal film, a high cavity effect appears and the directivity of light emission and color purity can be further improved. Moreover, as such an Ag thin film, it is preferable to laminate an Ag thin film on the surface of the electrode layer facing the opposite electrode of the electrode layer from the viewpoint of causing the Ag thin film to function as an electrode.

  Furthermore, the thickness of such a silver thin film is preferably less than 50 nm, and more preferably 10 to 45 nm. When the thickness of such a silver thin film exceeds the upper limit, the transmittance is lowered, and the effect of improving the directivity and color purity of light emission cannot be sufficiently obtained, and the light emission luminance of the organic EL element tends to decrease. On the other hand, if it is less than the lower limit, the reflectance tends to decrease, and the effect of improving the directivity of light emission and color purity tends to be lost.

In addition, as the organic EL element according to the present invention, configurations other than the light emitting layer and the electrode layer are not particularly limited, and a known organic EL element including the light emitting layer and the electrode layer can be appropriately used. An organic EL device that further includes a hole transport layer, a hole blocking layer, an electron transport layer, a cathode buffer layer, an anode buffer layer, and the like may be used. Although it does not restrict | limit especially as a structure of such an organic EL element, For example, the organic EL element of a structure as shown to the following (A)-(E) can be used suitably.
(A) Anode / silver thin film / light emitting layer / electron transport layer / cathode (B) anode / silver thin film / hole transport layer / light emitting layer / electron transport layer / cathode (C) anode / silver thin film / hole transport layer / Light emitting layer / hole blocking layer / electron transport layer / cathode (D) anode / silver thin film / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (E) anode / silver thin film / Anode buffer layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode.

  In addition, materials such as the hole transport layer, the hole blocking layer, the electron transport layer, the cathode buffer layer, and the anode buffer layer are not particularly limited, and can be used to form the hole transport layer described above. These materials can be used as appropriate. Further, the thickness of the hole transport layer, hole blocking layer, electron transport layer, cathode buffer layer, anode buffer layer, and the like are not particularly limited, and may be appropriately changed according to the design of the organic EL element. Is possible. Furthermore, the manufacturing method of such a hole transport layer, hole blocking layer, electron transport layer, cathode buffer layer, anode buffer layer and the like is not particularly limited, and a known method can be adopted. Moreover, the shape in particular of such an organic EL element is not restrict | limited, According to the design of the target organic EL composite element, the shape can be changed suitably.

  The organic EL device according to the present invention is preferably formed on a substrate. As a substrate related to such an organic EL element, there is no particular limitation on the kind of glass, plastic and the like, and there is no particular limitation as long as it is transparent, but preferred substrates include, for example, glass, quartz, A light transmissive resin film can be mentioned. Moreover, as such a resin film, a well-known resin film can be used suitably, For example, a polyethylene terephthalate (PET), a polyethylene naphthalate (PEN), polyether sulfone (PES) etc. are mentioned. In addition, an inorganic or organic film or a hybrid film of both may be formed on the surface of the resin film.

  In the organic EL composite element of the present invention, the liquid crystal material is laminated on the surface of the light extraction surface of the organic EL element. The method of laminating the liquid crystal film on the light extraction surface of the organic EL element is not particularly limited. For example, the liquid crystal film is fixed to the surface of the organic EL element by heat fusion, or fixed via an adhesive or an adhesive. A method etc. can be adopted.

  Next, the organic EL display device of the present invention will be described. An organic EL display device according to the present invention includes the organic EL composite element according to the present invention. Such an organic EL display device is not particularly limited except that the organic EL composite element of the present invention is used, and other configurations can be the same as those of a known organic EL display device. Moreover, such a display device can be used as, for example, a display device, a display, or various light emission sources. In a display device or a display, full-color display is possible by using three types of organic EL elements of blue, red, and green light emission. Examples of the display device and display include a television, a personal computer, a mobile device, an AV device, a character broadcast display, and an information display in a car. In particular, it may be used as a display device for reproducing still images and moving images, and the driving method when used as a display device for reproducing moving images may be either a simple matrix (passive matrix) method or an active matrix method.

  Next, the lighting device of the present invention will be described. The illuminating device of the present invention comprises the organic EL composite element of the present invention. Such an illuminating device is not particularly limited except that the organic EL composite element of the present invention is used, and the other configuration can be the same as a known illuminating device. In addition, such lighting devices include home lighting, interior lighting, backlights for watches and liquid crystals, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, Examples include, but are not limited to, a light source of an optical sensor.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

( Comparative Example 1 )
An organic EL composite element in which a liquid crystal film was laminated on the surface of the light extraction surface of the organic EL element was manufactured by the following method. The organic EL composite device manufactured in this way has a structure as shown in FIG. 1 (cathode 1 / electron injection layer 2 / light emitting layer 3 / hole transport layer 4 / hole injection layer 5 / transparent electrode 6 / Glass substrate 7 / transparent support substrate 8 / left twisted cholesteric liquid crystal film 9A / right twisted cholesteric liquid crystal film 9B / transparent support substrate 10).

  First, an organic EL element was manufactured. That is, first, an ITO layer having a thickness of 100 nm is laminated as the transparent anode 7 on the surface of the glass substrate 8, and then a CuPc (copper phthalocyanine complex) layer as the hole injection layer 5 is laminated 10 nm on the surface of the transparent anode 7. Furthermore, a TPD (N, N′-bis (3-methylphenyl) -N, N-7-diphenyl- [1,1-biphenyl] -4,4′-diamine) layer as the hole transport layer 4 is 45 nm. Laminated. Next, an Alq (aluminum complex) layer having a thickness of 60 nm was laminated as the light emitting layer 3 on the surface of the hole transport layer 4, and then LiF (lithium fluoride) as an electron injection layer 2 was 1 nm on the surface of the light emitting layer 3. Further, an Al thin film of 0.2 μm was laminated as the cathode 1 on the surface of the electron injection layer 2 to produce an organic EL element. In the organic EL element thus obtained, the glass substrate 7 serves as a light extraction surface.

  Next, a right-twisted cholesteric liquid crystal film and a left-twisted cholesteric liquid crystal film were respectively produced. That is, first, a liquid crystal mixture of polymer achiral nematic liquid crystal composed of aromatic polyester and polymer chiral nematic liquid crystal composed of aromatic polyester (LC film manufactured by Nippon Oil Corporation) was dissolved in chloroform. Thus, a polymer cholesteric liquid crystal solution was produced. The mixing ratio of the polymer chiral nematic liquid crystal in such a liquid crystal mixture was 93 wt%, and the concentration of the mixture in the polymer cholesteric liquid crystal solution was 10 wt%. Next, two types of triacetyl cellulose films (alignment substrates) having a rubbing polyimide layer were prepared, and the resulting polymer cholesteric liquid crystal solution was formed on each alignment substrate by spin coating, under a temperature condition of 135 ° C. Heat treated for 5 minutes. Thus, a right-twisted cholesteric liquid crystal film and a left-twisted cholesteric liquid crystal film were obtained, respectively. When the cholesteric liquid crystal film thus obtained was measured with a stylus type film thickness meter, the film thickness was 2.0 μm. Moreover, the pitch number of the helical structure of the cholesteric liquid crystal film obtained in this way was 6 respectively.

  Next, on the surface of the triacetyl cellulose layer 80 μm as the transparent support substrate 8, a left-twisted cholesteric liquid crystal film 9 A (2 μm) is passed through an adhesive (trade name “Aronix UVX-3400” manufactured by Toagosei Co., Ltd.). The film precursor (A) was obtained by adopting a method of fixing and laminating. Next, a right-twisted cholesteric liquid crystal film 9B (2 μm) is placed on the surface of the 80 μm triacetyl cellulose layer as the transparent support substrate 10 via an adhesive (trade name “Aronix UVX-3400” manufactured by Toagosei Co., Ltd.). The film precursor (B) was obtained by adopting a method of immobilization and laminating. Thereafter, the film precursor (A) and the film precursor (B) are overlapped so that the liquid crystal film 9A and the liquid crystal film 9B are adjacent to each other, fused and fixed by heat, and the right twisted cholesteric liquid crystal film and the left A liquid crystal film laminated with a twisted cholesteric liquid crystal film was obtained. Then, the liquid crystal film was laminated on the light extraction surface of the glass substrate 7 of the organic EL element obtained as described above by using a method of fixing via an adhesive.

(Example 1 )
2 (cathode 1 / electron injection layer 2 / light emitting layer 3 / hole transport layer 4 / hole injection layer 5 / silver thin film 11 / transparent electrode 6 / glass substrate 7 / transparent support substrate 8 / left An organic EL composite element of twisted cholesteric liquid crystal film 9A / right twisted cholesteric liquid crystal film 9B / transparent support substrate 10) was produced.

First, an organic EL device was produced in the same manner as in Comparative Example 1 except that a 42 nm thick silver thin film was laminated between the transparent electrode 6 and the hole injection layer 5 by vapor deposition. And the organic EL composite element was manufactured by adopting the same method as in Comparative Example 1 except that the organic EL element thus obtained was used.

(Comparative Example 2 )
An organic EL element similar to the organic EL element manufactured in Comparative Example 1 was used as an organic EL composite element for comparison without laminating a liquid crystal film. That is, the organic EL composite element for comparison has a configuration of cathode 1 / electron injection layer 2 / light emitting layer 3 / hole transport layer 4 / hole injection layer 5 / transparent electrode 6 / glass substrate 7.

[Evaluation of characteristics of the organic EL composite element produced in Example 1及 beauty Comparative Example 21 to]
<Measurement of reflectance of liquid crystal film>
In order to evaluate the characteristics of the liquid crystal film laminated on the organic EL element in Comparative Example 1 and Example 1 , first, a liquid crystal film having the same configuration as the liquid crystal film laminated in Comparative Example 1 and Example 1 (transparent support substrate) 8 (80 μm) / left-twisted cholesteric liquid crystal film 9A (2 μm) / right-twisted cholesteric liquid crystal film 9B (2 μm) / transparent support substrate 10 (80 μm)) was produced (Synthesis Example 1). In addition, this liquid crystal film was manufactured by adopting the same method as that adopted in Comparative Example 1 . And the natural light was irradiated with respect to the liquid crystal film obtained in this way, and the reflectance was measured. A graph showing the relationship between the light transmittance of the liquid crystal film obtained in Synthesis Example 1 and the light wavelength is shown in FIG.

  As is clear from the results shown in FIG. 3, the liquid crystal film obtained in Synthesis Example 1 in which left-handed and right-twisted cholesteric liquid crystal films are laminated has a specific wavelength region (a wavelength region of about 530 nm to 590 nm). It was confirmed that the light transmittance was greatly reduced and the transmittance was approximately 10% or less. From these results, it was confirmed that the liquid crystal film had very high light reflectance in the wavelength region and had selective reflection characteristics.

<Measurement of emission spectrum>
Example 1及 beauty Comparative Example 1 using the organic EL composite device as prepared to 2, each of the organic EL composite element at a temperature 25 ° C. by applying a constant current of 2.5A / cm ^2, each of the organic EL composite element Was measured with a fiber multichannel spectroscope USB2000 (Ocean Optics). The obtained results are shown in FIGS. Incidentally, the emission spectrum of the organic EL composite element produced in Comparative Example 1 shown in FIG. 4, the emission spectrum of the organic EL composite element produced in Example 1 shown in FIG. 5, prepared in Comparative Example 2 Organic The emission spectrum of the EL composite element is shown in FIG. 6, the half width of the emission spectrum of the organic EL composite element manufactured in Example 1 and Comparative Example 2 is shown in FIG. 7, and manufactured in Example 1 and Comparative Example 2 . The viewing angle dependence of the organic EL composite element is shown in FIG.

As is clear from the results shown in FIGS. 4 to 7, the organic EL composite element (Comparative Example 1) that does not include the cholesteric liquid crystal film in the laminated structure exhibits a relatively broad emission spectrum, and the viewing angle ranges from 0 ° to 40 °. It was confirmed that the light emission intensity did not change so much even when it was swung to 0 ° (FIG. 6). On the other hand, in the case of the organic EL composite element of the present invention ( Comparative Example 1 and Example 1 ) in which a liquid crystal film was laminated, the emission spectrum was narrowed as compared with Comparative Example 2 . In addition, in the organic EL composite element of the present invention ( Comparative Example 1 and Example 1 ), it was confirmed that the emission intensity was greatly reduced when the viewing angle was changed (FIGS. 4 and 5). Furthermore, from the results shown in FIGS. 5 and 7, the emission spectrum is narrowed by laminating a liquid crystal film and forming a silver thin film having a thickness of 42 nm on the electrode layer of the organic EL element. This confirmed that the color purity was further improved. In addition, in the silver thin film which has a film thickness of 50 nm or more, the transmittance | permeability fell extremely and the emission spectrum could not be observed.

Further, from the results shown in FIG. 8, the organic EL composite element (Example 1 ) of the present invention has sufficiently high directivity of light emission compared to the organic EL composite element (Comparative Example 2 ) for comparison. Was confirmed. FIG. 8 is normalized by the emission intensity in the direction of the viewing angle of 0 °.

  From these results, in the organic EL composite element of the present invention, it was confirmed that by laminating the liquid crystal film, the color purity of the emission spectrum was improved and the emission was concentrated in the normal direction of the emission surface. It was done. In addition, such a result shows that by using a cholesteric liquid crystal film, which is a one-dimensional photonic crystal, a cavity structure is formed between the electrodes, and light emission is concentrated at the band edge of the selective reflection wavelength region. This is presumably due to the increased directivity of light emission.

  As described above, according to the present invention, it is possible to efficiently manufacture without using a dielectric multilayer film that is difficult to manufacture, and to have a light emission directivity as high as when a dielectric multilayer film is used. It becomes possible to provide an organic EL composite element capable of realizing color purity, an organic EL display device using the same, and an illumination device.

  Therefore, the organic EL composite element of the present invention is particularly useful as an organic EL composite element used in various display devices, lighting devices, and the like because it is excellent in light emission directivity and color purity.

6 is a schematic diagram of an organic EL composite element manufactured in Comparative Example 1. FIG. 1 is a schematic diagram of an organic EL composite element manufactured in Example 1. FIG. It is a graph which shows the relationship between the light transmittance of the liquid crystal film obtained by the synthesis example 1, and the wavelength of light. 5 is a graph of an emission spectrum of an organic EL composite element manufactured in Comparative Example 1 . 2 is a graph of an emission spectrum of the organic EL composite element manufactured in Example 1 . 5 is a graph of an emission spectrum of an organic EL composite element manufactured in Comparative Example 2 . 5 is a graph of the half-value width of an emission spectrum of an organic EL composite element manufactured in Example 1 and Comparative Example 2 . It is a graph which shows the viewing angle dependence of the organic electroluminescent composite element manufactured in Example 1 and Comparative Example 2 .

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cathode, 2 ... Electron injection layer, 3 ... Light emitting layer, 4 ... Hole transport layer, 5 ... Hole injection layer, 6 ... Transparent electrode, 7 ... Glass substrate, 8 ... Transparent support substrate, 9A ... Left twisted cholesteric Liquid crystal film, 9B ... right twisted cholesteric liquid crystal film, 10 ... transparent support substrate, 11 ... silver thin film.

Claims (7)

At least a light emitting layer , a substrate of any one of glass, quartz, and a light transmissive resin film, a light extraction surface side electrode layer laminated on the substrate, a counter electrode, and a light extraction surface side electrode An organic EL device comprising a silver thin film laminated on the surface of the surface facing the opposite electrode of the layer ;
A liquid crystal film having a photonic band gap that is selectively reflected on a light extraction surface of the organic EL element and selectively reflects light of a specific wavelength;
Equipped with a,
The liquid crystal film is a liquid crystal film in which a right-handed cholesteric liquid crystal film and a left-handed cholesteric liquid crystal film are laminated, and
A cavity structure is formed by the opposite electrode of the organic EL element and the liquid crystal film;
An organic EL composite element characterized by the above. The selective reflection wavelength region of the liquid crystal film, the organic EL composite element according to claim 1, characterized in that overlaps at least a portion of the emission wavelength region of the organic EL element. 3. The organic EL composite element according to claim 1, wherein the liquid crystal film has a spiral structure formed of liquid crystal molecules, and the pitch number of the spiral structure is 1 to 30. The liquid crystal film, the organic EL composite element according to any one of claims 1 to 3 in which the liquid crystal material, characterized in that is obtained by immobilizing the After cholesteric orientation in a liquid crystal state . The thickness of the said silver thin film is less than 50 nm, The organic EL composite element as described in any one of Claims 1-4 characterized by the above-mentioned. An organic EL display device comprising the organic EL composite element according to any one of claims 1 to 5 . An illuminating device comprising the organic EL composite element according to any one of claims 1 to 5 .

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